Cathode Active Material Reducing DCIR in Low SOC Batteries
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Solution Overview
Problem
Current lithium-ion rechargeable batteries face challenges in improving input/output characteristics, particularly in reducing direct-current resistance (DCIR) at low state of charge (SOC) levels below 20%, which affects battery performance and safety.
Innovation Solution
The development of a cathode active material comprising layered hexagonal crystal lithium nickel manganese composite oxide particles, expressed by the formula Li1+u Ni x Mn y Co z M t O 2, with specific ratios of Na, Mg, Ca, and SO4, and controlled crystallite size and particle size, optimized through a crystallization, mixing, and calcination process to enhance the integrated intensity ratio and reduce DCIR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional lithium nickel cobalt manganese composite oxide is used as cathode material, then high voltage (4V class) and high energy density are achieved, but direct-current resistance increases in low SOC states (below 20%), deteriorating input/output characteristics
Solution Approach 1:
The invention changes the crystal structure parameters by controlling the integrated intensity ratio I(003)/I(104) to be 1.05 or greater through specific calcination conditions (temperature, time, atmosphere), which modifies the crystal orientation and reduces DCIR in low SOC states while maintaining high voltage and energy density
Solution Approach 2:
The invention uses composite lithium nickel cobalt manganese oxide with specific elemental composition (Li1+uNixMnyCozMwO2 where M is Al, Ti, V, Cr, Zr, Nb, Mo, or W) to achieve both high energy density and improved input/output characteristics by combining multiple metal elements with complementary properties
2Reliability
If additional elements are introduced into lithium nickel cobalt manganese composite oxide to improve cycling characteristics and reduce resistance, then charge/discharge cycling characteristics and low resistance are improved, but crystal structure stability may be compromised
Solution Approach 1:
The invention introduces additional elements (Al, Ti, V, Cr, Zr, Nb, Mo, or W) at specific local positions in the crystal structure (substituting at Ni, Co, or Mn sites) to improve cycling characteristics while maintaining overall crystal structure stability through controlled substitution rather than random distribution
Solution Approach 2:
The invention optimizes the composition parameters (x, y, z, w values and u for lithium excess) to balance the stabilizing effects of additional elements with the need to maintain the layered hexagonal crystal structure, achieving both improved cycling characteristics and structural stability
3Reliability
If crystal growth is promoted during calcination to improve battery characteristics, then crystallinity is improved, but particle size increases which may reduce surface area and affect performance
Solution Approach 1:
The invention optimizes calcination parameters (temperature, time, atmosphere composition) to achieve the desired integrated intensity ratio I(003)/I(104) ≥ 1.05 while controlling particle growth, balancing crystallinity improvement with surface area retention through precise parameter control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces DCIR in low SOC states while maintaining high capacity, leading to improved input/output characteristics and enhanced battery performance, including capacity retention and thermal stability.
Implementation Method 1
a crystallization process for obtaining nickel manganese composite hydroxide particles that include secondary particles that are formed from an aggregation of plural primary particles
Implementation Method 2
a calcination process for obtaining lithium nickel manganese composite oxide particles by performing calcination of the lithium mixture in an oxidizing atmosphere and at a calcination temperature of 850°C to 1000°C
Data Source
Figure 1~2
AI summary
To provide a cathode active material for a non-aqueous electrode rechargeable battery, with which it is possible to improve input/output characteristics, particularly by reducing resistance in a low SOC state in which DCIR increases, and to provide a manufacturing method for same. The cathode active material includes layered hexagonal crystal lithium nickel manganese composite oxide particles represented by the general formula (A): Li1+uNixMnyCozMtO2 (where 0 ≤ u ≤ 0.20, x + y + z + t = 1, 0.30 ≤ x ≤ 0.70, 0.10 ≤ y ≤ 0.55, 0 ≤ z ≤ 0.40, 0 ≤ t ≤ 0.10, and M is one or more elements selected from Al, Ti, V, Cr, Zr, Nb, Mo, and W), and further including Na, Mg, Ca and SO4, in which the total amount of Na, Mg and Ca is 0.01 to 0.1 mass%, the amount of SO4 is 0.1 to 1.0 mass%, and the ratio of the integrated intensity of the diffraction peak on plane (003) to that on plane (104) obtained by powder X-ray diffraction measurement using CuKα rays is 1.20 or greater.